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of Empire House, 159 Great Charles Street, Birmingham, 3. Telephone: CENtral 7777. Telegraphic Address: "Empirical, Birmingham". (1937)
'Credenda' Works in Oldbury, Worcestershire; 'Simplex' Works in Garrison Lane, Birmingham.
1919 Tube Investments was registered as a public company combining the seamless steel tube manufacturing companies of Tubes Limited, Credenda Conduits Co, Star Tube Co and St. Helen's Tube and Metal, as well as Simplex Conduits Ltd.
1932 Recognising the scope for improvement in the management of its electrical subsidiaries, Tube Investments formed a new organisation that would be responsible for the manufacture and sale of electrical products. Simplex Conduits merged with Credenda Conduit Co to form Simplex Electric Co which began to manufacture Creda domestic cooking appliances in addition to lighting equipment and conduits.
1933 Creda electric cooker with oven. With a cast metal hotplate-griller and a red-ring hotplate (later addition). One of the early electric cookers to be fitted with a Credastat automatic oven thermostat - patented by the Credenda Conduit Co Ltd, Birmingham 1931. Whole cooker enamelled in mottled pale grey, made by Simplex Electric Co Ltd, of Birmingham. Used daily in the donor's home from 1934 to 1967. Credastat was an optional extra on Creda cookers at this time. Inscription on oven door: Creda/BRITAINS BEST/ELECTRIC. Made by Simplex Electric Co - Birmingham
1937 British Industries Fair Advert for 'Creda' Electric Cookers; Fires; Water Heaters; Tubular Heaters; Wash Boilers; Irons; Kettles; Toasters; canteen Equipment, etc. and 'Simplex' Electrical Installation Equipment, comprising Conduits, Fittings, Switchgear, Industrial Lighting Equipment, Flameproof Lanterns, Floodlights, Mersey Cables. (Electricity: Industrial and Domestic Section - Stand Nos. Cb515 and Cb.414) 
1961 Patent - Improvements in and relating to electric immersion water heaters. 
1962 Patent - Improvements in and relating to electric switchboards. 
1967 The original company name, Simplex Steel Conduit Co, had been brought back into use for electrical conduit.